Conventionally, various exhaust heat recovery devices provided in an exhaust system of an automobile or the like having an internal combustion engine and recovering exhaust heat are proposed (see, for example, Patent Documents 1 to 6). As such an exhaust heat recovery device, for example, a flow path of exhaust gas is configured to switch between a heat exchanger on an exhaust system and a bypass path bypassing the heat exchanger by opening and closing a valve body of the exhaust system according to an operating state of an internal combustion engine and a temperature of a medium (cooling water).
For example, Patent Document 1 discloses an exhaust heat recovery apparatus configured such that a temperature-operated actuator for opening a valve body when a temperature of a medium reaches a predetermined value or more is provided, and the valve body is configured to be opened when at least one of the flow rate of exhaust gas and the temperature of the medium is equal to or higher than a predetermined value. In the exhaust heat recovery apparatus configured as above, when the flow rate of the exhaust gas increases and reaches a predetermined value, the valve body is opened and the bypass path is opened, and the exhaust gas passes through the bypass path by bypassing the heat exchanger on the exhaust system. Therefore, in the exhaust heat recovery apparatus disclosed in Patent Literature 1, it is said that a flow resistance of the exhaust gas in the exhaust system can be reduced.
In addition, Patent Document 2 discloses an exhaust heat recovery apparatus configured such that exhaust gas passing through an exhaust pipe passes through a gap between an outer circumference of the exhaust pipe and a laminate, and then flows out through a gap between jacket elements to a downstream side from a gap between an inner circumference of a cylindrical shell and the laminate. Patent Document 3 discloses an exhaust heat recovery apparatus including an exhaust pipe, a heat exchanger, an exhaust port, an opening and closing means for opening and closing an outlet of the exhaust pipe, and a shell member for guiding exhaust gas discharged from the outlet and the discharge port to a downstream side. Patent Document 4 discloses an exhaust heat recovery apparatus including a heat exchanger which performs heat exchange between exhaust gas and a medium, and a bypass path by which exhaust gas bypasses the heat exchanger, in an exhaust system of an internal combustion engine or the like. Patent Document 5 discloses an exhaust heat recovery device including an exhaust heat recovery device body, a thermoactuator, and a recovery efficiency switching valve which is opened and closed to a recovery side or a non-recovery side in association with an operation of an output unit of the thermoactuator.
Patent Document 6 discloses a heat exchanger using a honeycomb structure as a first fluid circulating portion through which a heating body passes. The honeycomb structure has a plurality of cells which is defined and formed by ceramic partition walls and penetrates in an axial direction from one end face to the other end face and through which a heating body that is a first fluid passes.
In addition, conventionally, as an exhaust heat recovery device for recovering exhaust heat as described above, an exhaust heat recovery device including an exhaust gas recirculation (EGR) cooler has also been proposed (see, for example, Patent Documents 7 and 8).